The present invention relates generally to an adjuster mechanism for automobile headlamps and the like, and relates more specifically to an improved gearbox construction for use with such mechanisms with novel means for providing a degree of prevailing torque.
Modern automobile constructions are designed to take advantage of aerodynamics and to present an aerodynamically efficient profile. Toward this goal, the old sealed beam headlamps have given way to composite headlamp constructions which merge smoothly with the aerodynamic profile of the car body. Also, these lamps employ improved, state-of-the-art lighting technology.
Because of the aerodynamic shape of the lamps, it is necessary that adjustment of the horizontal and vertical orientation of the headlamps take place from under the hood of the automobile.
As proper orientation of the automobile headlamps is essential to driving safety, these headlamps must retain the desired orientation during service. That is to say, the vibrations and jarring of the auto experienced in normal use must not vibrate the headlamps out of adjustment. Also, when misalignment occurs, it is necessary that an owner or mechanic can readily and easily re-adjust the headlamps to a proper orientation.
To provide and assure the desired headlamp orientation, headlamp adjuster mechanisms for the vertical and horizontal are normally provided for each headlamp. The construction and functionality of adjuster mechanisms for automobile headlamps and the like are well known to those skilled in the relevant art, as is evident, for example, by the following United States patents.
______________________________________ Hirose et al. 4,916,587 04/10/90 Lisak 4,893,219 01/09/90 Allen 4,882,658 11/21/89 Nakamura 4,843,523 06/27/89 Eckenrode et al. 4,796,494 01/10/89 Ryder et al. 4,713,739 12/15/87 Saijo et al. 4,689,725 08/25/87 Ryder et al. 4,674,018 06/16/87 Furfari et al. 4,665,469 05/12/87 ______________________________________
These adjuster mechanisms function well. However, due to the vibration and jostling commonly attendant with driving a car, the adjuster mechanisms may move or rotate, and thereby change the orientation of the headlamp for a desired pre-set position. In order to prevent this from occurring, a source of prevailing torque is built into the mechanism. Prevailing torque is the term given to a form of resistive force or friction applied to one or more of the movable elements of the adjuster mechanism which overcomes any tendency of the components to vibrate out of position during normal service.
Means must be provided for applying some degree of prevailing torque to the adjuster mechanism. This means must be controllable and predictable in order to meet automobile manufacturer's exacting specifications, yet must permit movement or adjustment of the components as needed. The present invention provides a unique and improved means for applying the prevailing torque to an adjuster mechanism.